Air conditioning units are particularly useful for regulating the climate in an enclosed space. Currently, air conditioning units are used for cooling the interior spaces of vehicles, such as recreational vehicles, mobile homes, boats, and tractor trailer cabs. The most common type of existing air conditioning unit has the compressor connected directly to the vehicle's engine. These units operate only while the vehicle's engine is running.
As a result of this requirement that the air conditioning unit only operate while the vehicle's engine is running, some existing mobile air conditioning units provide means for connecting it to an alternating current (AC) supply outlet. The limited availability of AC supply outlets; however, limits the utility of this alternative. While vehicles, such as recreational vehicles, mobile homes and boats are primarily used by their owners to escape from the confines of modern society, AC supply outlets are only available in certain fixed locations, such as a primary camp site. In most instances, however, hooking-up to an AC supply outlet is impractical or undesirable. The problem is that the vehicle must be taken to the AC supply outlet. As a result, vehicle owners lose the freedom to take their vehicles to the places they desire. Consequently, owners of those vehicles are unable to maximize their enjoyment of the vehicle because of the limitations in the availability of AC supply outlets.
Other existing mobile air conditioning units are powered by auxiliary power supplies located in the vehicle. Some systems even provide auxiliary air conditioning units that can be used when the main air conditioning units cannot be operated. Those systems that contain auxiliary components, however, are very bulky and are very expensive to install and operate.
The limitations of existing air conditioning units are exemplified in the problems faced by tractor trailer drivers. Often times, drivers will sleep in the cab while they are on the road. When drivers become tired, they pull off to the side of the road or into a designated rest area. Unfortunately, AC supply outlets are rarely, if ever available, at those locations to power an air conditioning unit. As a result, the driver must make a decision whether to forego cooling/heating or to leave the vehicle's engine running so that the air conditioning unit does not drain the battery. If the air conditioning unit is not operating, the climate in the cab may become unbearable. If the vehicle's engine is left running for a long period of time, serious damage could result to the engine and, at a minimum, the engine's life span will be greatly reduced. Furthermore, the driver risks death from carbon monoxide poisoning. Existing direct current air conditioning units, however, will quickly drain the vehicle's battery. After only a couple of hours of operation, the battery may be drained to such an extent that the battery will not have enough power to start the vehicle's engine.
Existing mobile air conditioning units are very inefficient. To compensate for this inefficiency, existing units utilize more power by connecting batteries in parallel. This, however, greatly increases the expense of the unit. Typically, air is blown with a squirrel cage blower over an aluminum fin tube heat exchanger. Aluminum evaporators also create a significant amount of condensate which creates a problem with condensate drip. Consequently, the warm air return/cool air delivery system on existing systems must be configured in such away that condensate does not drip down into the cooled area. As a result cool air delivery vents must be positioned to deliver cool air against the flow of the natural air currents of the cooled area.
A need, therefore, exists for a mobile air conditioning unit that can be operated on a DC power source for extended periods of time while the vehicle's engine is not running.
While there are numerous methods and means for air conditioning a vehicle, none are known to have a similar structure to, or to function in the manner of, the present invention.